(1) Field Of The Invention
This invention relates to an intermittent positive pressure breathing apparatus and, in particular, to an improved mouthpiece accessory for that apparatus.
(2) Description Of The Prior Art
While an intermittent positive pressure breathing (IPPB) apparatus is commonly used whenever a patient needs ventilation, such an apparatus also is used in respiratory therapy, to supply liquid medication in aersol form to, e.g., the lungs and bronchi. Such an apparatus, in general, functions to provide gaseous pressure for inhalation by a patient, until the patient's lungs expand and sufficient back pressure is built up to cause the inward pressure to automatically terminate, and allow the patient to exhale, before pressure is again applied by the breathing apparatus.
The positive pressure breathing apparatus comprises an elongated flexible tube which is connected at one end with a gas delivery apparatus. The other end of the tube, i.e., the free end, is provided with a mouthpiece for introduction into a patient's mouth, between his teeth. Where the patient is conscious and cooperative, and is able to, the patient grips the mouthpiece between his teeth and, in this way, the mouthpiece is retained within his mouth. Thus, a seal is maintained to prevent loss of gaseous pressure. Where gaseous pressure is lost, as by the escape of gas from the patient's mouth, sufficient back pressure is often not built up to shut off the incoming gas, to terminate the inhalation cycle. Accordingly, the patient is prevented from exhaling, as desired.
In many cases, however, the patient may be under an anesthetic or infirm, or otherwise unable on his own, to retain the mouthpiece within his mouth. Thus, it becomes necessary, not only to place the mouthpiece within the patient's mouth, but also provide that it is retained within the patient's mouth, as desired, and that a proper seal is provided against escape of gas. One means of accomplishing this is shown in U.S. Pat. No. 2,857,911. Another more recent mouthpiece accessory and seal is disclosed in U.S. Pat. No. 4,030,493.
As disclosed in U.S. Pat. No. 4,030,493 the mouthpiece of the positive pressure breathing apparatus can be provided with a disposable flexible ovate convex, concave shaped faceplate which can be pressed against the areas above and below a patient's mouth and the areas adjacent the mouth extremities. That disposable faceplate is characterized by a ridge on the periphery of the concave side that tapers toward the faceplate in both directions from the center of the faceplate. Thus, a ridge is provided which is of the greatest height at the center, and of lesser height at the extremities of the ovate shape. Moreover, the width of the ridge at the extremities, as disclosed in the patent, is considerably less than in the center sections.
While either of these mouthpieces now commercially used has been satisfactory to a degree, neither has provided entirely satisfactory performance. The mouthpiece disclosed in U.S. Pat. No. 2,857,911 is not only generally not disposable because of its cost, its construction does not lend itself to ease in cleaning, for re-use. Even though the mouthpiece accessory disclosed in U.S. Pat. No. 4,030,493 is of quite simple construction, and its manufacture economical so that its cost permits it to be disposable, the structural features of that mouthpiece does not always provide an adequate seal against escaping gas.